There is a conventionally known automatic transmission installed in a vehicle or the like that performs a so-called neutral control. In the neutral control, when the vehicle running in a driving range is stopped by a foot brake or the like, the engagement of a clutch (e.g. C-1) that accomplishes power transmission from an engine to a drive wheel is relaxed to achieve a substantially neutral state (see Patent Document 1). A control device for an automatic transmission according to Patent Document 1 increases the engagement pressure of the clutch by a preset pressure if a clutch drag state is determined, and decreases the engagement pressure of the clutch by the preset pressure if a clutch slip state (power transmission state) is determined, thereby maintaining the clutch in a state immediately prior to the slip state (immediately prior to performing power transmission).
In cases where the neutral control that achieves this type of drag state (state immediately before the slip state) is performed, when the vehicle is stopped, torque converter drag (creep torque transmission) can be suppressed to improve fuel economy and the transmission of engine vibrations to the vehicle body can also be suppressed; meanwhile, when the vehicle starts off, the clutch can be immediately engaged to secure a power transmission response at start off and ensure that the driver and others do not sense a delay in the transmission of drive power.